A study of the occurrence, specific activities, substrate affinities and inhibitors of the purine and pyrimidine metabolizing enzymes of a number of trypanosomid (Kinetoplastid) flagellates. Special attention will be given to the unique deaminating enzymes for the purine bases regarding their kinetic properties and their inhibition by a number of agents. The organisms to be used for these studies include Trypanosoma cruzi, Leishmania donovani, L. braziliensis, L. tarentolae and L. mexicana.